<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        input[type='radio']{
            appearance: none;
            width: 20px;
            height: 20px;
            line-height: 20px;
            text-align: center;
            background-color: #ccc;
            border-radius: 50%;
            vertical-align: middle;
        }
        input[type='radio']:checked{
            background-color: red;
        }
        input[type='radio']:checked:after{
            content: "\2713";
            color: white;
        }
    </style>
</head>
<body>
    <input type="radio" name="gender" value="male" checked>男
    <input type="radio" name="gender" value="female">女
</body>
</html>